Process for manufacturing metal coated thread



March 1 193s.- m K,FUJE"TAL 2,109,839

PROCESS FOR MANUFACTURING METAL COATED THREAD Filed Dec. 9, 1933INVENTORS:

BY SM Jmal'.

vii.

A'TTORNEYS.

Patented Mar. 1, 1938 UNITED STATES l PROCESS FOR MANUFACTURING METALooaran THREAD Kitaro Fujii, Otomura, Nakakouchi-gun, Prefecture Osaka,and Seiichiro Iwamoto, Osaka,

Japan 1 Application December @1933, Serial No. 701,722

In Japan December 19, 1932 r 2 Claims.

This invention relates to a process for manufacturing metal coatedthread, and its object is to produce easily and economically a metalcoated thread of greater strength and higher luster than i has beenapplied, through metallic dust.- The 10 thread'thus manufactured lackssufllcient lustre, smooth surface, and is not perfectly round. Also thenetallic'powder comes off easily, and is not satisfactory in practicaluse.

In'accordance with this invention, we have made use of small pieces ofmetal leaf instead of metallic powder, and put them into a solution ofpaste. The metal leaves,-in suspension in the solution of paste,ar.e puttin a core thread by drawing the thread through a special capillarytube. Such capillary tube isput on or forms the tip of a graduallyconverging nozzle and has the diameter corresponding to thefinishedthread before the paste has become dry, thereby obviating theabove mentioned defects, and providing excellent metal coated thread.

This we consider to be novel, and our invention will be betterunderstood by reference to the following specification and appendedclaims when considered in connectionwith the accompanying 30 drawing.

Fig. 1 is an enlarged sectional view of a capillary nozzle hayinggradually converging diameter for carrying this invention into effect;Figs. 2 and 3 are enlarged sectional views showing expansible capillarynozzle tips. l Referring to Fig. 1 of the drawing, l represents acapillary tube fitted to the ,tip end of a capillary nozzle 5 which issupplied with the solution 40 of paste 2 with the thin metallic leaves 3insuspension. The thread 4 is drawn through the gradually convergingnozzle andcapillary tube. Then the thread comes out of the capillarytube with a uniform coating of small leaves of metal foil.

Thread is not generally uniform in diameter, having lumps and joints, inwhich case the capillary tubes as shown in Figs. 2 and 3 are preferablyused; The capillary tubes as shown in Figs. 2 and 3 are made of flexibletubular metal plate,

having overlapping portions 6 and l which are 55 pands automatically, asshown in Fig. 3 to accommodate the irregularities, thereby preventing,the breaking of the thread. For this purpose, a capillary tube,consisting of two or more separatepieces, joined together to accommodateirregularities in the diameter, may equally be used.

In another way of carrying this invention into effect, the same objectcan be attained by passing the thread through the solution of pastehaving the metal leaves in suspension. The thread thus 10 coated withthe metallic leaves is drawn through the capillary nozzle having agradually converging circular hole. 7 i

' Now we will explain an actual example more in detail.

The mixed solution of 3.37% of cotton nitrate;

v 16.74% of butyl acetate; 13.95% of acetone;

27.97% of benzene; 4.46% of ester gum; 28.57% of butylphthalate is mixedwith six parts of liquid consisting of 4 parts of benzene and 6 parts ofether to obtain a viscous paste. This paste is put in acontainerprovided with a capillary nozzle I at its one extremity asshown in Fig. 1. Small pieces of metal leaf 3, smaller than 50 mesh, of

an alloy consisting of copper, tin, zinc and iron, 7

having specific gravity of 7.93, are put into the paste 2. The thread41s passed through the paste in the direction ofthe arrow a at the speedof 20 centimeters per second; The metallic leaves I 3 suspended in thepaste will be subject to the force as shown by arrows. b due to theforward movement of the thread 4, which will bring the leaves floatingat random in the broader part of the convergent nozzle, in positionsparallel with the surface of the thread in the tip of capillary tube I.When the thread is drawn thru the cap.- illary tube, the flat leaves arepressed firmly on to the thread surface and attached thereto as if theywere wound. Metal coated thread thus manufactured has high lustre anddurability 40 against abrasion. It also has other useful characteristicssuch as strong tensile strength and uniformity of diameter and finish.

All in tals generally consist of an aggregation of fine c stals, eacharranged irregularly in in- 'definite directions, therefore thepowder'obtained by crushing such metal gives diffused reflections on thesurface, and has unsatisfactory lustre. On the other hand ithas beenfound by X-ray'analysls, that small pieces of thin metal leaf ob- 5tained by cold press work has a fibrous texture in which the crystalsare arranged in parallel with the flat surface of the leaf giving betterluster on the surface than on the section. In this 1 invention we havemade use of thethin metal leaf as the necessary condition for improvingmetal coated thread.

Since thread generally consists of an assembly of a number of singlefibres twisted together, there are, many spaces and irregularities init. In order to increase the strength of the metal covered thread andthe durability of the metal-covering, it is necessary to utilize theabove mentioned spaces for containing as much paste aspossible, andpressing the metal leaves very firmly thereon.

As above described, in accordance with this invention, a capillarynozzle is used which has a gradually converging inner diameter, whilethe nozzle tip has a diameter almost equal to that of a finished thread.When the thread isgto be coated, the leaves are firmly pressed onto thesurface of the thread, guided by the inner wall of the graduallyconvergent capillary nozzle while passing therethroughl The metal coatedthread manufactured by the method of the present invention has such construction that the ,flat surface of each thin metal leaf is firmlypressed onto the surface of the core thread in parallel thereto, causinga very desirable lustre, owing to the special shine inherent "solutionwhich contains a quantity of very small flat metal flakes in suspensionand flnally pulling out said thread through a; capillary nozzle having agradually converging orifice and having a nozzle tip of an interiordiameter almost equal to that of a thread to be finished,.said capillarynozzle and nozzle tip being filled with the paste solutioncontainingsaid metal flakes in suspension and said gradually convergent nozzleacting to collect the metal flakes-towards the nozzle tip by themovement of the core thread therethrough so as to cause the metal flakesto be deposited and accumulated uniformly and evenly around the threadand firmly pressed together to incorporate with the surface of saidthread in passing through the nozzle tip.

2. The method of manufacturing metallic threads, such as golden orsilver threads, which consists in drawing a core thread through a pastesolution which contains a quantity of very small fiat metal flakes insuspension and finally pulling out said thread through a capillarynozzle having a gradually converging orifice and having a resilientlyexpansible nozzle tip of an interior diameter almost equal to that of athreadto be finished and capable of expanding to allow for inequalitiesin the thread, said capillary nozzle and nozzle tip being filled withthe paste solution containing said metal flakes in suspension and saidradually convergent nozzle acting to collect the metal flakes towardsthe nozzle tip by the movement of the core thread therethrough so as tocause the metal flakes to be deposited and accumulated uniformly andevenly around the thread and firmly pressed together to incorporate withthe surface of said thread in passing through the nozzle tip. KITAROFUJII.

SEIICHIRO IWAMOTO.

